Re: Expansion symbolic
- To: mathgroup at smc.vnet.net
- Subject: [mg74754] Re: Expansion symbolic
- From: "Dominic Jackson" <dr.kjackson at gmail.com>
- Date: Wed, 4 Apr 2007 03:54:52 -0400 (EDT)
Could anyone please tell me how to instruct Mathematica to expand the
expression below with respect to the powers of x. I would like the
constants c1,c2,c3 and c4 to stay behind the summation sign but the powers
of x to cross over to multiply x^(k+i).
(c1 (x^2) +c2 (x^3))* D[(Summation sign i=0 to infinity) Subscript[a,i+1][k]
* x^(k+i),{x,2}]//Expand.
This is what I get
c1 x^2 *(Summation sign i=0 to infinity) (k+i)*(k+i-1) *Subscript[a,i+1][k]
* x^(k+i-2)
+ c2 x^3 *(Summation sign i=0 to infinity) (k+i)*(k+i-1)
*Subscript[a,i+1][k] * x^(k+i-2)
And this is what I want to achieve.
c1 *(Summation sign i=0 to infinity) (k+i)*(k+i-1) *Subscript[a,i+1][k] *
x^(k+i)
+ c2 *(Summation sign i=0 to infinity) (k+i)*(k+i-1) *Subscript[a,i+1][k] *
x^(k+i+1)
Any clues.
Thanx.
Dom